Printed circuit board assemblies (PCBs) with electrical components are used in computers, communications equipment, televisions, and many other products. A PCB is generally a laminated board with circuit traces on one or both external surfaces and sometimes inside the board. A wide variety of electrical components are mounted on one or both external surfaces of the circuit board, such as processors, memory devices, clocks, resistors, capacitors and virtually any other type of electrical component. The electrical components may be individually attached to selected locations on the external surfaces of the PCB with a solder paste, or several similar electrical components may be mounted to an interface unit that is attached to the printed circuit board. The electrical components may be attached to the interface units or PCBs with a solder paste using through-hole mounting or surface mounting techniques. Since the electronics manufacturing industry is highly competitive, it is important to maximize the throughput of PCB assemblies while reducing the waste of operable components.
To surface mount electrical components to a PCB, pads of solder paste are printed onto the PCB, and then the components are pressed against the solder pads. The PCB and the components are subsequently placed in a solder reflow oven that melts the solder particles in the solder paste to bond and electrically couple the components to the PCB. In a typical PCB assembly process, many PCBs may be fully assembled into market-ready products in a short period of time.
One important aspect of manufacturing PCB assemblies is to recover operable components from unusable PCB assemblies. PCB assemblies may not be usable because the board is defective or components attached to the board are defective. Also, PCB assemblies may not be usable because a customer may request design changes after many PCB assemblies have been partially or fully assembled. In either case, it is desirable to salvage and reuse the operable electronic components from the unusable PCB assemblies.
To recover operable electronic components from unusable PCB assemblies, the operable electronic components are detached from the interface units or PCBs so that they may be reused on another PCB assembly. One conventional process for salvaging electronic components is to place a plurality of PCBs or interface units onto a plate and heat the components in a solder reflow oven of a PCB assembly line until the solder melts. Each PCB or interface unit is then individually lifted and tapped against the plate to dislodge the components. The plate may simply be an old PCB or a rigid sheet that is the correct size and shape to ride on the conveyor rails of the reflow oven.
Several problems exist with the conventional process for salvaging electronic components from unusable PCB assemblies. One problem is that the salvage process is time-consuming and it uses the reflow ovens of the PCB assembly line. Accordingly, salvaging operable components from unusable PCB assemblies interrupts the normal processing of marketable PCB assemblies. Conventional salvage processes, therefore, may reduce the throughput of normal PCB assembly operations.
Another problem with conventional component salvage processes is that the yield of operable salvage components may be relatively low. As the PCBs or interface units are tapped against the plate, several components may land on the plate in contact with another component while the solder is in a molten state. As a result, several components may stick to one another after the solder cools to a solid state. Additionally, some components may even bounce off of the plate and fall into the reflow oven. Therefore, in conventional salvage processes, many components may have to be reheated or are simply lost in the reflow oven.
In light of the problems associated with conventional salvage processes, it would be desirable to increase the throughput and yield for salvaging electrical components from unusable PCB assemblies.